Electron discharge tube



Dec. 22, 1931.

G. HOLST ET AL 1,837,437

ELECTRON DISCHARGE TUBE lfiled Ma\ 14, 1923 4 Sheets-Sheet 1 is 3 L a 19so If 10 ID I! 15 *fiL m as Dec. 22, 1931.

G. HOLST ET AL ELECTRON DISCHARGE TUBE Filed May 14, 1925 4 Sheets-Sheet2 15% W WW Dec. 22, 1931. HQLST AL 1 ,837,437

ELECTRON DISCHARGE TUBE Filed May l4 1923 4 Sheets-Sheet I5 Dec. 22,1931.

G. HOLST ET AL 1,837,437

ELECTRON DISCHARGE TUBE Filed May 14, 1923 4 Sheets-Sheet 4 5115M hfifli f *O MMM [Haw (M (Z W 41 I ad ,6 7/ 4:06 J

Patented Dec. 22, 1-931 UNITED STATES PATENT I OFFICE ASSIGNORS TONAAMLOOZE VENNOO'ISCHAP PHILIPS GLOEILAMPENFABRIEKEN, 0]

EINDHOVEN, NETHERLANDS ELECTRON DISCHARGE TUBE Application filed Kay 14,1928, Serial No. 688,932, and in the Netherlands October 21, 1922.

This invention relates to electron discharge tubes and more particularlyto discharge tubes provided with a sealed envelope wh ch consists atleast partly of vitreous material. Still more particularly the inventionrelates to the attachment of one or more electrodes in the interior ofsuch discharge tubes. The invention is applicable to discharge ,tubessuch as'X-ray tubes, rectifiers, tubes provided with three or moreelectrodes for wireless telegraphy, telephony and similar purposes,having either a high vacuum or a gaseous filling.

v The invention is particularly advantageous when applied totransmitting or receiving tubes of high capacity for wirelesstelegraphy, telephony and similar purposes.

For the attachment of the grid and the anode in tubes with threeelectrodes, resilient clamps or similar devices have hitherto been used,to which the electrodes were fixed by means of supports.

The object of the present invention is an improvement of theattachmentof electrodes and more particularly its object is to provide asimple and rigid construction, where only a small quantity of metal isused for the attachment. v

The discharge tube according to the invention, which is provided with asealed envelope consisting at least partly of vitreous material, ischaracterized in that within said envelope at least one electrode issupported by at least one 'bar shaped support fixed to a connectingmember, said member being fused to the glass of the tube along a portionof its surface materially larger than the surface of the end of abar-shaped support. The connecting member consists at least at theplace, of fusing-in, of a metallic material which readily adheres to thevitreous material of the envelope and which has a coeflicient of thermalexpansion differing little from that of the vitreous material. As amaterial for the connecting-member chrome-iron containing 10-50% ofchromium is particularly suitable;

The electrode can be connected to the connetting-member (preferablyannular) by means of one or more chrome-iron supports.

The invention is particularly advantageous when one or moresealing-members are fused with the wall or the end of a glass tube,which 1s hermetically closed and is fused withthe y tgeous or metallicwall of the discharge- The glass tube can be hermetically closed 7 by aglass stem which is fused with the tube and 111 which one or moreleading-in wires are embedded. The tube may also be hermetically closedby a disc consisting of me: tallic material that does not generate gasesduring the fusing operation and has'a coeflicient of expansionsubstantially the same as that of the glass. Said disc is fused at itscircumference with the glass of the tube and serves for the passage andthe attachment of a leading-in wire.

The device according to the invention is particularly advantageous whenthe glass tube is hermetically closed by several discs of metallicmaterial that do not generate gases during the fusing operation and havea coeflicient of expansion substantially the same as that of the glass.Each of these discs can be used for the attachment of one leading-inwire and the discs are, at least along a portion of their circumference,hermetically connected together by a glass'layer. These discs have sucha shape that the remaining parts of their circumferences together corres0nd to the cross-section of the glass tube. referably the discs may beshaped as sectors or segments of a circle.

In the accompanying drawings some embodiments ofthe invention arediagrammatically represented by way of example.

Fig. 1 is a view of. a discharge-tube with three electrodes. The plateand the grid are fixed to glass tubes. I

Fig. 2 is an end-view on anenlarged scale of the glass tube thatsupports the grid and the filament according to Fig. 1.

Fig. "3 illustrates another construction of a fixing-device according tothe invention. The interior of the glass tube is closed by a glass stem,in which two leading-in wires are embedded.

vide with three electrodes, whlch are supported by one glass stem. Bymeans of supports the anode and the grid are fixed to metal rings whichare fused to the ends of two co-axial tubes and in the inner tube twosector-shaped discs carrying the filament are fused.

Fig. 5 is an end-view of the glass stem according to Fig. 4:.

Fig. 6 and Fig. 7 show a construction in which the connecting-member isnot ringshaped but comprises an arc-shaped plate.

Fig. 8 is an end-view of a construction similar to that shown in Figs. 6and 7. The glass tube is closed by three sector-shaped discs.

Fig. 9 shows the fixing of the glow-cathode in an X-ray tube, and

Fig. 10 shows a construction in which the sealing-member comprises aflat ring the circumference of which is fused with the wall of a glasstube contained in the bulb.

In the discharge tube with three electrodes shown in Fig. 1 theinvention is applied to the attachment of the anode and the grid. Theconstruction shown in the said figure is particularly advantageous forgenerating tubes of high capacity, for example more than 1 kilowatt, forwireless telegraphy, telephony and similar purposes.

The tube has a glass wall 1 with which the glass tubes 2 and 3 arehermetically fused. To the end of the glass tube 2 a metal ring'G isfused, to which the anode 1 is fixed by means of supports 5. Theinterior of the tube 2 is hermetically sealed by a glass stem 7, inwhich a leading-in wire 8 for the anode is embedded. In a similar mannera metal ring 9 is fused to the end of the glass tube 3 and the grid 11is fixed to said ring by means of bar-shaped supports 10. A leading-inwire 12 for the grid is fused at 13 in the wall of the tube.

As a material for the rings 6 and 9 any metal or metal alloy is suitablewhich readily adheres to glass and has a thermal coefiicient ofexpansion substantially the same as that of the glass, as otherwisecracks would occur in the glass when fusing the rings to the end of theglass tubes. It will however be apparent from the nature of theconstruction that the seal between the glass and the metal need not behermetic.

It has been found that chrome-iron of a certain composition isparticularly suitable as a material for the rings. The composition theso-called potassium sodium glass an alloy containin about 17-20% ofchromium has given satis actory results.

Small quantities of impurities may occur in the chrome-iron withoutdecreasing the suitability of the material. These impurities can havesome influence on the coeflicicnt of expansion, owin to which thecomposition must be somew at varied.

The impurities may have been introduced into the alloy because they werealready present in the elementary body such for example as carbon iniron, but it may also be necessary that, when melting together the twometals chromium and iron, small quantities of. certain admixtures, suchfor example as manganese or silicon, should be used. It is desirablehowever that the, percentage of the impurities should alwa s be small.

The thickness of t e metal ring should not be too small in connectionwith the attachment of the electrodes although the edge embedded in theglass should be thin. It has been found however that even chrome-ironrings having at the edges a thickness of 1 to 2 millimeters are veryreadily scaled to glass, which removes any difficulty experienced inthis respect.

Also metals or alloys other than chromeiron are suitable for the purposeof the invention. When using for instance the socalled Pyrex glass whichis frequently used in America, also molybdenum or tungsten are suitable.In the case of lead-glass or X-ray glass, nickel-iron which is freedfrom all occluded gases can be used whilst good results can also beobtained with the socalled compounded rings having for example anickel-iron core and a thin platinum layer. Platinum is less suitablefor the purpose of the invention as, in the first place, it is tooexpensive and moreover platinum rings having a relatively largethickness, to 1 mm. for example, are very difficult to fuse in.

The use of chrome-iron is also advantageous because, as a rule, thismaterial absorbs but a very little quantity of gas and consequently itgenerates but a small quantity of gas when introduced into the tube. Inconnection with the purpose of obtaining a high vacuum in the tube thisis a considerable advantage.

It is also possible to free the chrome-iron from occluded gases bymelting it in a vacuum, for example, prior to its introduction into thetube, although it is not necessary to do so.

The device for fixing the electrodes according to the invention isparticularly advautageous when combined with a process of leading thecurrent through, such as has been applied to the glass tube 3. Theinterior of the latter is sealed by two semi-circular discs 18 and 19 towhich leading-in wires 20 and 21 for the filament 15, 16 are fixed onboth sides.

As a material for the discs such metals or alloys are generally suitablewhich do not gen- .erate gases during the fusing operation,

which readily adhere to glass and which have a coeflicient of expansionsubstantially the same as that of the glass. 'As a rule the samematerials may be used as mentioned before for the rings 6 and 9 but theconditions tobe observed with regard to the discs are more severebecause a perfectly hermetic seal must be obtained. Again the use ofchrome-iron,

of suitable composition offers great advanta es.

' egarding the properties ofthe chromeiron the same remarks may be madeas those hereinbefore mentioned.

The process of leading the current through several discs which, along aportiono their periphery are hermetically connected together by a glasslayer whilst the remaining parts of their peripheries togethercorrespond to the cross-section of the glass tube.

- Generally the periphery of the discs connected together should be'acircle.

The discs may be shaped into any form desired. Preferably, care shouldbe taken that the discs canbe sealed together b a relatively thin glasslayer, after which t e free part of the periphery of at least onefof thediscs may be fused in the glass tube. One or more discs may, along thewhole of their periphery,

also be connected to the other disc or discs For example a circular andan annular disc may be connected by an intermediate glass ring, and thenthe annular disc with the glass tube may be melted together. Preferably,however, the disc consists of segments or seetors of a circle. Althoughnot necessary the most simple course is to use fiat discs and to connectthem by the surrounding glass to form one larger flat disc.

It is advisable that the discs, before being fused inthe glass tube,should be surrounded by a thin glass layer.

The leading-in wires may be fixed to the discs in various ways. The maybe led through holes in the discs and xed thereto by soldering, weldingor in any other way. In so doing, however, there is a risk of formingair-leaks in the seal and therefore the leading-in wires shouldbepreferabl fixed to the discs on both sides, as shown in ig. 1, bysoldering or welding for example. When chrome-iron discs are used it isdesirable that the parts of the leading-in wires that are fixed to thediscs should be made of nickel, as the latter metal isreadily and easilyfixed to chrome-iron by welding.

The use of chrome-iron as a material for the discs is also advantageousbecause the said material is practically non porous and permitsobtaining a permanent high vacuum within the tube.

The end of the glass tube 3 of 1 is illustrated on a larger scale inFig. 2.

Another embodiment of the invention is shown in Fig. 3; A lass tube isfused with the wall of adisc ar tube which is not shown. Said wall may eof glass or of metal. To the end of the tube 25 a ring 26 is fused in,to which the electrode is connected by means of supports 27. At theother end the tube 25 is hermetically sealed to a disc 30 by a stem 29,which is placed in the reverse manner to that commonly adopted. Such anarrangement of the stem offers the advanta e that the pinch 31 in whichthe leading-1n wir s 32 and 33 are embedded is more distant from thefilament 34, so that the pinch is pre- 7 vented from reaching too hi h atemperature; such as has been applied to the glass tube 3, is in generalcharacterized by the sealin in of In Fig. 4 a discharge tu e is shownprovided with three electrodes which are all supported on the same sideof the tube by a glass stem. A lass tube 36 is fused with the glass wallo? the discharge tube. The filament 44 is supported by its leading-inwires which are fixed to sector-shaped discs 45 and 46 whichhermetically seal the, interior of the glass tube 36. The grid 38 isconnected by supports 39 to a metal ring 37, which is fused to the endof the tube 36. A second tube 43, to the end of which a ring 42 isfused, is also fused with the said tube 36. The latter ring supports theplate 40 by means of bar-shaped supports 41. Leading-in wires 47 and 48for plate and grid are fused into the glass-wall of the tube in'theknown manner. The way of suspending the filament, the construction ofthe electrodes and their arrangement with relation to each other arealso known.

Fig. 5 is an end-view of the glass stem of the tube illustrated in Fig.4.

Fig. 6 represents diagrammatically an embodiment of the inventionrovided with an arc-shaped connecting-mem er instead of an annular onefor fixing the electrodes. To the end of the tube 50 two arc-shapedconnectingmembers 51 and 52 are fused, having attached thereto supports54 and 53 for fixing the'electrodes. The latter operation may beeffected in any suitable way for example by soldering or welding.

As a material for the supports nickel is suitable for all constructionsaccording to the invention.

The use of chrome-iron for the supports is particularly advantageous asthe small heatconductivity of said material prevents an undesiredheat-conduction to the glass.

The interior of the tube 50 is hermetically sealed by the stem 55, inwhich the leadingin wires 56 and 57 are embedded.

Fig. 8 is an end-view of a fixing-device provided withconnecting-members 61 and 62 of the same shape as those shown in Fig. 7.The glass tube is however hermetically sealed by three sector-shapeddiscs 58, 59 and 60, which may serve for example for fixing theleading-in wires for the filament and those for the grid and for leadingthem through.

In Fig. 9 an application is shown of the invention to X-ray tubes inwhich the device according to the invention is used for fixing theglow-cathode. A glass tube 66 to the end of which the ring 67 1s fused,is fused with the wall 65 of the tube. To said ring the supports 68 arefixed, to the end of which is attached a collecting-device 69. One endof the coiled filament ,73 is fixed to the collecting-device and theother end (the centre of the coil) is fixed to a leading-in wire 72which is embedded in the stem 70. The other leading-in wire 71 is fixedto one of the supports 68.

In the construction shown in Fig. 10 the sealing-member comprises a flatring of chrome-iron or any other suitable metallic material. Theinternal circumference of said ring is fused with the wall of aglasstube 80, which is hermetically fused with the wall of the dischargetube. The glass tube. is hermetically sealed at 81 and a leading-in wire82 is hermetically fused into the seal. The electrode 85 is connected tothe sealing-member 83 by metal supports 84 as in the otherconstructions. It is clear that also at other points the sealing-membermay be fused with the wall of the discharge tube.

It will be apparent to persons skilled in the art that where in the,accompanying drawings discharge tubes are shown, with a sealed envelopeentirely consisting of vitreous material, the present invention may alsobe applied to tubes the envelopes of which partly consist of metal; forexample vit may be applied to discharge tubes the anode of which formspart of the wall of the tube.

What we claim is:

1. An electrical discharge device comprising'a sealed envelope having 'are-entrant tubular stem of vitreous material, an electrode mounted in"said envelope, a support for said electrode comprising bars secured attheir upper ends to said electrode and having at their other ends aconnecting member of a metal having substantially the same co-efii cientof thermal expansion as said vitreous vmaterial, said connecting memberhaving a thin curved edge conforming in shape to and embedded in theoutside of the curved wall of said tubular vitreousstem by' fusion ofsaid vitreous material in juncture with said connecting member, acooperating'electrode mounted in said envelope, and leading-in wires forsaid electrodes hermetically sealed into the walls of said envelope andconnected to said electrodes.

2. An electrical discharge device comprising a sealed envelope having are-entrant glass stem with a tubular inner end, an electrode mounted insaid envelo e, a support for said electrode comprising ars secured attheir upper ends to said electrode and having on their other ends aconnecting member of a metal having substantially the same co-efiicientof thermal expansion as said glass and curved to conform to the shape ofthe inner end of said stem, one edge of said connectin member beingembedded in the end of sai tubular stem by fusion of said glass injuncture with said edge of said connecting member, a cooperatingelectrode mounted in said envelope, and leading-in wires for saidelectrodes hermetically sealed into the walls of said envelope andconnected to said electrodes.

3. An electrical discharge device comprising a sealed envelope having are-entrant glass stem with a tubular inner end, an electrode mounted insaid envelope, 2. support for said electrode comprising bars secured attheir upper ends to said electrode, and having at their other ends aring member of a metal having substantially the same coeflicient ofthermal expansion as said glass and having a thin edge curved to conformto the shape of the inner end of said stem and embedded in the outsideof the curved wall of said tubular stem near the inner end thereof byfusion of said glass in juncture with said thin curved edge of saidmember, a cooperating electrode mounted in said envelope, and leading-inwires for said electrodes hermetically sealed into the walls of saidenvelope and connected to said electrodes.

4. An electrical discharge device comprising a sealed envelope having are-entrant glass stem with a tubular inner end, an electrode havingsubstantially the same co-efiicient of 4 thermal expansion as said glassand of substantially the size and shape of the tubular inner end of saidstem, and having a thin curved edge embedded in the end of said tubularstem by fusion of said glass in juncture with said thin edge of saidring, a cooperating electrode mounted in said envelo e, and leading-inwires for said electro es hermetically sealed into the walls of saidenvelope and connected to said electrodes.

5. An electrical discharge device comprising a sealed envelope having are-entrant tubular glass stem, an anode mounted in said envelope, asupport for said anode comprising bars secured at their upper ends to i:

said anode and having at their other ends a connecting ring member of achrome iron alloy having substantially the same co-eilicient of thermalexpansion as said glass, said Ting ber having a thin curved edgeconhermetically connected together along their straight abuttin edges bya layer of glass to form an imper orate circular disc hermeticallysealed at its periphery to the inside walls of said stem to hermeticallyclose it, a conductor fixed to the inner surface of each of saidsemi-circular discs to project along the bore of said stem toward theinterior of said envelope, a filamentary cathode connected to saidconductors, a leading-in wire hermeticall sealed into the wall of saidenvelope an connected to said anode, and a current supply lead,connected to the exterior surface of each of said semi-circular discs.

In testimony whereof we aflix our signatures.

DR. GILLES HOLST. POPKO REINDER DIJKSTERHUIS.

